Radially cross-aligned nanofiber membrane

Abstract

A method for controlling fiber cross-alignment in a nanofiber membrane, comprising: providing a multiple segment collector in an electrospinning device including a first and second segment electrically isolated from an intermediate segment positioned between the first and second segment, collectively presenting a cylindrical structure, rotating the cylindrical structure around a longitudinal axis proximate to an electrically charged fiber emitter; electrically grounding or charging edge conductors circumferentially resident on the first and second segment, maintaining intermediate collector electrically neutral; dispensing electrospun fiber toward the collector, the fiber attaching to edge conductors and spanning the separation space between edge conductors; attracting electrospun fiber attached to the edge conductors to the surface of the cylindrical structure, forming a first fiber layer; increasing or decreasing rotation speed of the cylindrical structure to alter the angular cross-alignment relationship between aligned nanofibers in adjacent layers, the rotation speed being altered to achieve a target relational angle.

The invention claimed is: 
     
       1. A fiber membrane, comprising electrospun fiberizeable material in at least three adjacent layers of nanofibers, each layer comprising a plurality of aligned nanofibers oriented at oblique angles relative to nanofibers in adjacent layers, said plurality of aligned nanofibers in each layer extending from a first membrane edge to a second membrane edge, wherein a plurality of aligned nanofibers in each layer cross a plurality of aligned nanofibers in adjacent layers at a plurality of distinct points of intersection, forming a crossing at each distinct point of intersection consisting of three crossing nanofibers extending directionally as six radials from each of said distinct points of intersection, wherein relative cross-alignment angles between said six radials at each distinct point of intersection are in the range of 50 to 70 degrees, and wherein said relative cross-alignment angles of said aligned nanofibers and spacing between said aligned nanofibers each have a specific average numerical value in said membrane and comprise a structure having porosity required for cell migration and exudate flow from a wound, and wherein said aligned nanofibers comprise a polymer and any one or combination of a chromogenic agent, an antimicrobial agent, a hemostatic agent, an analgesic agent, a regenerative agent, an immune modulator, an oxygenating agent, and a pH stabilizer. 
     
     
       2. The fiber membrane of  claim 1 , wherein said nanofibers comprise any combination of natural or synthetic polymers. 
     
     
       3. The fiber membrane of  claim 1 , wherein said nanofibers further comprise any one or combination of poly (lactic-co-glycolic acid) (PLGA), polyvinylpyrrolidone (PVP), poly(ethyleneoxide) (PEO), polyurethane (PU), PVP/cyclodextrin, polyvinyl alcohol (PVA), polycaprolactone (PCL), cellulose, PVP/ethyl cellulose, PVP/zein, cellulose acetate, hydroxypropyl methylcellulose (HPMC), and analogues thereof. 
     
     
       4. The fiber membrane of  claim 1 , wherein said nanofibers further comprise an absorbable and biodegradable polymer that can be enzymatically or nonenzymatically decomposed, yields no toxic decomposition product, and has ability of releasing a drug. 
     
     
       5. The fiber membrane of  claim 1 , wherein said chromogenic agent is a dye presenting a color change response to enzymatic activity produced by pathogens present on human skin, in a wound bed, in wound exudate, or in bodily fluid. 
     
     
       6. The fiber membrane of  claim 5 , wherein said enzymatic activity produces lipase. 
     
     
       7. The fiber membrane of  claim 5 , wherein said pathogens include at least  Proteus mirabilis, Pseudomonas aeruginosa , and methicillin-resistant  Staphylococcus aureus  (MRSA). 
     
     
       8. A fiber membrane, comprising electrospun fiberizeable material in at least three adjacent layers of nanofibers, each layer comprising a plurality of aligned nanofibers oriented at oblique angles relative to nanofibers in adjacent layers, said plurality of aligned nanofibers in each layer extending from a first membrane edge to a second membrane edge, wherein a plurality of aligned nanofibers in each layer cross a plurality of aligned nanofibers in adjacent layers at a plurality of distinct points of intersection, forming a crossing at each distinct point of intersection consisting of three crossing nanofibers extending directionally as six radials from each of said distinct points of intersection, wherein relative cross-alignment angles between said six radials at each distinct point of intersection are in the range of 50 to 70 degrees, and wherein said relative cross-alignment angles of said aligned nanofibers and spacing between said aligned nanofibers each have a specific average numerical value in said membrane, and wherein said aligned nanofibers in each said layer comprise at least one of solid, hollow, or core-shell fiber, and wherein said nanofibers further comprise a polymeric material and a chromogenic agent responsive to enzymatic activity, and wherein said polymeric nanofibers further comprise an absorbable and biodegradable polymer that can be is-enzymatically or nonenzymatically decomposed, yields no toxic decomposition product, and has ability of releasing a drug. 
     
     
       9. The fiber membrane of  claim 8 , wherein said chromogenic agent is a dye presenting a color change response to said enzymatic activity produced by pathogens present on human skin, in a wound bed, in wound exudate, or in bodily fluid. 
     
     
       10. The fiber membrane of  claim 9 , wherein said enzymatic activity produces lipase. 
     
     
       11. The fiber membrane of  claim 9 , wherein said pathogens include at least  Proteus mirabilis, Pseudomonas aeruginosa , and methicillin-resistant  Staphylococcus aureus  (MRSA). 
     
     
       12. The fiber membrane of  claim 8 , wherein said polymeric material comprises any one or combination of poly (lactic-co-glycolic acid) (PLGA), polyvinylpyrrolidone (PVP), poly(ethyleneoxide) (PEO), polyurethane (PU), PVP/cyclodextrin, polyvinyl alcohol (PVA), polycaprolactone (PCL), cellulose, PVP/ethyl cellulose, PVP/zein, cellulose acetate, hydroxypropyl methylcellulose (HPMC), and analogues thereof.